require "ffi"
require "pathname"

module Minilab
  class MinilabHardware #@private
    include MinilabConstants

    def setup_error_handling(reporting, handling)
      create_error_hash cbErrHandling(reporting, handling)
    end

    def declare_revision(revision)
      memory = FFI::MemoryPointer.new :float
      memory.write_float(revision)
      create_error_hash cbDeclareRevision(memory)
    end

    def get_revision
      dll_revision_number = FFI::MemoryPointer.new :float
      vxd_revision_number = FFI::MemoryPointer.new :float
      error = cbGetRevision(dll_revision_number, vxd_revision_number)
      create_error_or_value_hash(error, dll_revision_number.read_float)
    end

    def get_error_string(error)
      message = FFI::MemoryPointer.new :char, ERRSTRLEN
      new_error = cbGetErrMsg(error, message)
      if new_error != 0
        create_error_hash(new_error)
      else
        message.read_string
      end
    end

    def configure_auxport(optz)
      raise ":pin is a required parameter" if optz[:pin].nil?
      raise ":direction is a required parameter" if optz[:direction].nil?
      create_error_hash cbDConfigBit(BOARDNUM, AUXPORT, optz[:pin], optz[:direction])
    end

    def configure_port(optz)
      raise ":port is a required parameter" if optz[:port].nil?
      raise ":direction is a required parameter" if optz[:direction].nil?
      create_error_hash cbDConfigPort(BOARDNUM, optz[:port], optz[:direction])
    end

    def read_analog(channel)
      raw_data = FFI::MemoryPointer.new :ushort
      error = cbAIn(BOARDNUM, channel, BIP10VOLTS, raw_data)
      return create_error_hash(error) if error != 0

      voltage = FFI::MemoryPointer.new :float
      error = cbToEngUnits(BOARDNUM, BIP10VOLTS, raw_data.get_ushort(0), voltage)
      create_error_or_value_hash(error, voltage.read_float)
    end

    def read_digital_pin(pin)
      data = FFI::MemoryPointer.new :ushort
      error = cbDBitIn(BOARDNUM, FIRSTPORTA, pin, data)
      create_error_or_value_hash(error, data.get_ushort(0))
    end

    def read_auxport(pin)
      data = FFI::MemoryPointer.new :ushort
      error = cbDBitIn(BOARDNUM, AUXPORT, pin, data)
      create_error_or_value_hash(error, data.get_ushort(0))
    end

    def read_port(port)
      data = FFI::MemoryPointer.new :ushort
      error = cbDIn(BOARDNUM, port, data)
      create_error_or_value_hash(error, data.get_ushort(0))
    end

    def write_analog(channel, volts)
      raw_data = FFI::MemoryPointer.new :ushort
      error = cbFromEngUnits(BOARDNUM, UNI5VOLTS, volts, raw_data)
      return create_error_hash(error) if error != 0
      error = cbAOut(BOARDNUM, channel, UNI5VOLTS, raw_data.get_ushort(0))
      create_error_hash(error)
    end

    def write_digital_pin(pin, data)
      create_error_hash cbDBitOut(BOARDNUM, FIRSTPORTA, pin, data)
    end

    def write_auxport(pin, data)
      create_error_hash cbDBitOut(BOARDNUM, AUXPORT, pin, data)
    end

    private
    def create_error_or_value_hash(error, value)
      error != 0 ? { :error => error } : { :value => value }
    end

    def create_error_hash(error)
      create_error_or_value_hash(error, true)
    end

    MCC_LIBRARY = Pathname.new(__FILE__).dirname.join("..", "..", "vendor", "mcc", "cbw32.dll")
    extend FFI::Library
    ffi_lib MCC_LIBRARY

    attach_function "cbErrHandling", [:int, :int], :int
    attach_function "cbDeclareRevision", [:pointer], :int
    attach_function "cbGetRevision", [:pointer, :pointer], :int
    attach_function "cbGetErrMsg", [:int, :pointer], :int
    attach_function "cbDConfigBit", [:int, :int, :int, :int], :int
    attach_function "cbDConfigPort", [:int, :int, :int], :int
    attach_function "cbAIn", [:int, :int, :int, :pointer], :int
    attach_function "cbToEngUnits", [:int, :int, :ushort, :pointer], :int
    attach_function "cbFromEngUnits", [:int, :int, :float, :pointer], :int
    attach_function "cbDBitIn", [:int, :int, :int, :pointer], :int
    attach_function "cbDIn", [:int, :int, :pointer], :int
    attach_function "cbAOut", [:int, :int, :int, :ushort], :int
    attach_function "cbDBitOut", [:int, :int, :int, :ushort], :int
  end
end